With the microwave technology, data is directly transmitted over the air without the need of deploying optical fibers or cables. The microwave technology has obvious engineering advantages in cities, remote areas, or special areas (for example, river). The microwave technology features convenient networking, flexible usage, and short service deployment time. With the development of the microwave technology, the cost of the microwave device is gradually reduced. Therefore, the microwave technology becomes increasingly widely used.
Certain phenomena affect the transmission quality of microwave signals in microwave technology. For example, the non-linear amplifier leads to signal distortion, and the inband fluctuation of the channel filter leads to the imbalance of the gain. To improve the transmission quality of microwave signals, the signal to noise ratio (SNR) of the transmitter needs to be improved. This problem is solved generally through error correction.
The existing error correction method is as follows: extracting certain transmit signals of the transmitter; obtaining a feedback IQ signal after performing sampling through the downward frequency conversion, band-pass filter, and analog to digital converter (ADC); calculating by the error calculation unit the error signal of the transmission channel according to the original IQ signal and the feedback IQ signal; performing pre-distortion processing for the transmitted data according to the error signal; and then transmitting the data through the transmission channel.
The existing error correction technology has at least the following disadvantages: The sampling circuit, downward frequency converter, band-pass filter, and ADC need to be provided, which directly increases the system cost and power consumption. In addition, only the error of the transmitter can be corrected, but the error introduced by the receiver cannot be corrected.